Post-deployment calibration for wireless position determination

ABSTRACT

Methods and apparatuses are directed to calibrating a misconfigured wireless access point. One method may include receiving a position of mobile station(s) and wireless signal model measurements derived from packets exchanged between the mobile station(s) and a plurality of wireless access points, receiving positions and/or identities of the plurality of wireless access points used in determining the position of the mobile station(s), comparing a position of the mobile station(s) with wireless signal model measurements, and identifying a misconfigured wireless access point based upon the comparing. Another method may include receiving positions associated with a plurality of wireless access points, determining a position of a mobile station based upon a wireless signal model, comparing the position of the mobile station and the wireless signal model with the positions associated with the plurality of wireless access points, and determining whether at least one wireless access point is misconfigured.

CLAIM OF PRIORITY UNDER 35 U.S.C. §119

This application is a continuation of U.S. application Ser. No.12/643,676, entitled “POST-DEPLOYMENT CALIBRATION FOR WIRELESS POSITIONDETERMINATION,” filed Dec. 21, 2009, which issued as U.S. Pat. No.8,768,344 on Jul. 1, 2014 and claims the benefit of and priority to U.S.Provisional Application No. 61/139,928 entitled “INDOOR WLAN NETWORKCALIBRATION FOR POSITIONING” filed Dec. 22, 2008, each of which isassigned to the assignee hereof and hereby expressly incorporated byreference herein.

FIELD OF DISCLOSURE

Aspects of this disclosure generally relate to wireless communicationsystems, and more specifically, to the use of post-deploymentcalibration for wireless network position determination.

REFERENCE TO CO-PENDING APPLICATIONS FOR PATENT

The present Application for Patent is related to the followingco-pending U.S. Patent Applications:

“WIRELESS POSITION DETERMINATION USING ADJUSTED ROUND TRIP TIMEMEASUREMENTS” by Aggarwal et al., having Ser. No. 12/622,289, filed onNov. 19, 2009, assigned to the assignee hereof, and expresslyincorporated by reference herein.

“A METHOD AND APPARATUS FOR PROVIDING AND UTILIZING LOCAL MAPS ANDANNOTATIONS IN LOCATION DETERMINATION” by Das et al., having Ser. No.12/641,225, filed on Dec. 17, 2009, assigned to the assignee hereof, andexpressly incorporated by reference herein.

BACKGROUND

Mobile communications networks are in the process of offeringincreasingly sophisticated capabilities associated with the motionand/or position location sensing of a mobile device. New softwareapplications, such as, for example, those related to personalproductivity, collaborative communications, social networking, and/ordata acquisition, may utilize motion and/or position sensors to providenew features and services to consumers. Moreover, some regulatoryrequirements of various jurisdictions may require a network operator toreport the location of a mobile device when the mobile device places acall to an emergency service, such as a 911 call in the United States.

In conventional digital cellular networks, position location capabilitycan be provided by Advanced Forward Link Trilateration (AFLT). AFLT maycompute the position of a wireless device from the wireless device'smeasured time of arrival of radio signals transmitted from a pluralityof base stations Improvements to AFLT have been realized by utilizinghybrid position location techniques, where the mobile device may employa Satellite Positioning System (SPS) receiver. The SPS receiver mayprovide position information independent of the information derived fromthe signals transmitted by the base stations. Moreover, positionaccuracy can be improved by combining measurements derived from both SPSand AFLT systems using conventional techniques. Additionally, with theincreased proliferation of micro electro-mechanical systems (MEMS),small, on-board sensors may be used to provide additional relativeposition, velocity, acceleration and/or orientation information.However, position location techniques based upon signals provided by SPSand/or cellular base stations may encounter difficulties when the mobiledevice is operating within a building and/or within urban environments.In such situations, multipath and/or degraded signal strength cansignificantly reduce position accuracy, and can slow the “time-to-fix”to unacceptably long time periods.

Such shortcomings of SPS and cellular positioning may be overcome byexploiting signals used existing wireless data networks, such as Wi-Fi(e.g., Institute of Electrical and Electronics Engineers (IEEE) 802.11xstandards) and/or WiMAX (IEEE 802.16), and having elements within thenetwork infrastructure derive position information of the mobile device.Techniques used in such wireless data networks may exploit round triptime (RTT) and/or signal strength measurements (RSSI) derived fromsignals utilized within these networks. Utilizing such measurementtechniques to accurately determine position typically involves knowledgeof the configuration of various elements within the network, such as,for example, the location of the wireless access points/femtocells, etc.

In practice, some network elements used for position determination maynot be properly configured, and such misconfigurations could adverselyimpact the accuracy of the determined position solution. For example, ifwireless access point is moved to a different location and the locationit reports is not updated, positions determined using the old locationof the wireless access point may be unacceptably inaccurate.

Accordingly, it may be desirable to implement calibration techniqueswhich can update and/or compensate for improperly configured networkelements to maintain position determination accuracy, while reducingcostly post-deployment efforts for network infrastructure maintenance.

SUMMARY

Exemplary embodiments of the invention are directed to apparatuses andmethods for post-deployment calibration for use in wireless positiondetermination. In one embodiment, a method for calibrating amisconfigured wireless access point used for determining a position of amobile station is presented. The method may include receiving a positionof at least one mobile station and wireless signal model measurementsderived from packets exchanged between the at least one mobile stationand a plurality of wireless access points. The method may furtherinclude receiving positions and/or identities of the plurality ofwireless access points used in determining the position of the at leastone mobile station and comparing a position of the at least one mobilestation with wireless signal model measurements. The method may furtherinclude identifying a misconfigured wireless access point based upon thecomparing.

In another embodiment a method for calibrating a misconfigured wirelessaccess point at a mobile station is presented. The method may includereceiving positions associated with a plurality of wireless accesspoints, and determining a position of the mobile station based upon awireless signal model. The method may further include comparing theposition of the mobile station and the wireless signal model with thepositions associated with the plurality of wireless access points, anddetermining whether at least one wireless access point is misconfigured.

In yet another embodiment, an apparatus for calibrating a misconfiguredwireless access point used for determining a position of a mobilestation is described. The apparatus may include a wireless transceiver,a processing unit coupled to the wireless transceiver, and a memorycoupled to the processing unit. The memory may store executableinstructions and data which cause the processing unit to receive aposition of at least one mobile station and wireless signal modelmeasurements derived from packets exchanged between the at least onemobile station and a plurality of wireless access points. Additionalinstructions stored in memory may cause the processing unit to receivepositions and/or identities of the plurality of wireless access pointsused in determining the position of the at least one mobile station,compare a position of the at least one mobile station with wirelesssignal model measurements, and identify a misconfigured wireless accesspoint based upon the comparing.

In yet another embodiment, a mobile station which calibrates amisconfigured wireless access point is presented. The mobile station mayinclude a wireless transceiver, a processing unit coupled to thewireless transceiver, and a memory coupled to the processing unit. Thememory may store executable instructions and data for causing theprocessing unit to receive positions associated with a plurality ofwireless access points, determine a position of the mobile station basedupon a wireless signal model, compare the position of the mobile stationand the wireless signal model with the positions associated with theplurality of wireless access points, and determine whether at least onewireless access point is misconfigured.

Various embodiments may benefit from having the network and/or mobilestations compensate for improperly configured network elements. Suchadvantages can reduce network operating costs by reducing the number ofpost deployment inspections and maintenance calls for system upkeep.Further, various embodiments can also potentially lead to more accuratepositioning, when the locations and existence of network elements areaccurately known.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are presented to aid in the description ofembodiments of the invention and are provided solely for illustration ofthe embodiments and not limitation thereof.

FIG. 1 is a diagram of an exemplary operating environment for one ormore mobile stations in communications with a network consistent with anembodiment of the disclosure.

FIG. 2 is a block diagram illustrating various components of anexemplary mobile station.

FIG. 3 is a block diagram illustrating various components of anexemplary Positioning Server (PS).

FIG. 4 is a drawing illustrating an exemplary embodiment showing anumber of Local Area Network-Wireless Access Points (LAN-WAPs)communicating with a mobile station, wherein one LAN-WAP ismisconfigured.

FIG. 5 is a diagram showing an embodiment where a positioning server mayestimate the actual position of the misconfigured LAN-WAP usinginformation derived from a plurality of mobile stations.

FIG. 6 is a flow chart illustrating an embodiment of a calibrationprocess which may be performed by the positioning server.

FIG. 7 is a flow chart illustrating an embodiment of a calibrationprocess which may be performed by the mobile station.

DETAILED DESCRIPTION

Aspects of the invention are disclosed in the following description andrelated drawings directed to specific embodiments of the invention.Alternate embodiments may be devised without departing from the scope ofthe invention. Additionally, well-known elements of the invention willnot be described in detail or will be omitted so as not to obscure therelevant details of the invention.

The word “exemplary” is used herein to mean “serving as an example,instance, or illustration.” Any embodiment described herein as“exemplary” is not necessarily to be construed as preferred oradvantageous over other embodiments. Likewise, the term “embodiments ofthe invention” does not require that all embodiments of the inventioninclude the discussed feature, advantage or mode of operation.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of embodiments ofthe invention. As used herein, the singular forms “a”, “an” and “the”are intended to include the plural forms as well, unless the contextclearly indicates otherwise. It will be further understood that theterms “comprises”, “comprising,”, “includes” and/or “including”, whenused herein, specify the presence of stated features, integers, steps,operations, elements, and/or components, but do not preclude thepresence or addition of one or more other features, integers, steps,operations, elements, components, and/or groups thereof.

Further, many embodiments are described in terms of sequences of actionsto be performed by, for example, elements of a computing device. It willbe recognized that various actions described herein can be performed byspecific circuits (e.g., application specific integrated circuits(ASICs)), by program instructions being executed by one or moreprocessing units, or by a combination of both. Additionally, thesesequence of actions described herein can be considered to be embodiedentirely within any form of computer readable storage medium havingstored therein a corresponding set of computer instructions that uponexecution would cause an associated processing unit to perform thefunctionality described herein. Thus, the various aspects of theinvention may be embodied in a number of different forms, all of whichhave been contemplated to be within the scope of the claimed subjectmatter. In addition, for each of the embodiments described herein, thecorresponding form of any such embodiments may be described herein as,for example, “logic configured to” perform the described action.

As will be presented in more detail below, the position determination ofa mobile station may rely upon information derived from signalsexchanged between the mobile station and a plurality of wireless accesspoints/femtocells, etc. Such signal-derived information may include forexample, round trip time (RTT), received signal strength/received signalstrength indicator (RSS/RSSI) and/or Angle of Arrival (AoA). Auxiliaryinformation regarding the wireless access points, such as, for example,their location described in a reference coordinate frame, may also beused. The signal-derived information and the auxiliary information maybe utilized along with one or more wireless signal models (e.g., RTT,RSSI and/or AoA based models) to provide accurate estimates of positionfor the mobile station. If any type of auxiliary information provided tothe wireless signal model(s) is incorrect, and/or if a parameter usedwithin a wireless signal model is inaccurate, the position solution ofthe mobile station may be degraded. For example, if the position of awireless access point is incorrect because it was moved, and itslocation was not updated to reflect its new location, the improperlyconfigured wireless access point may adversely affect the positionsolution accuracy for mobile station.

As used herein, the term “misconfigured wireless access point” may beused to designate a wireless access point which is associated with anytype of incorrect, outdated, or missing piece of information.Accordingly, a misconfigured wireless access point may be associatedwith an incorrect location and/or any inaccurate parameter (e.g., adelay time, signal power decay, etc.) used within the wireless signalmodel(s). Calibration approaches described herein may be used todiscover and correct the misconfigured wireless access points withouthaving to manually perform such corrections. Because these techniquesmay be performed automatically, they can be useful after the network isinitially set-up and deployed (i.e., post-deployment).

FIG. 1 is a diagram of an exemplary operating environment 100 for one ormore mobile stations 108 in communications with a network consistentwith an embodiment of the disclosure. The operating environment 100 maycontain one or more different types of wireless communication systemsand/or wireless positioning systems. In the embodiment shown in FIG. 1,a Satellite Positioning System (SPS) may be used as an independentsource of position information for the mobile stations 108. Each mobilestation 108 a-108 c may include one or more dedicated SPS receiversspecifically designed to receive signals for deriving geo-locationinformation from the SPS satellites 102.

The operating environment 100 may also include a back end network (alsoreferred to herein as a back haul network) which may include a wide areanetwork. The back end network may include one or more wired and/orwireless networks, and can also provide Internet and/or cellular datanetwork access. The back end network may further include one or moreWide Area Network Wireless Access Points (WAN-WAPs) 104, which may beused for wireless voice and/or data communication, and potentially asanother source of independent position information for the mobilestations 108. The WAN-WAPs 104 may be incorporated into wireless widearea network (WWAN), which may include cellular base stations at knownlocations, and/or other wide area wireless systems, such as, forexample, WiMAX (e.g., 802.16). The WWAN may further include one or moreControllers 114 (such as, for example, a Base Station Controller), and aGateway 120 to interconnect the WWAN with a wide area network 118. Otherknown network components may further be included but are not shown inFIG. 1 for simplicity. Typically, each WAN-WAPs 104 a-104 c within theWWAN may operate from fixed, known positions, and provide networkcoverage over large metropolitan and/or regional areas.

The back end network may further include a separate positioning server(PS) 112, which may be connected to the wide area network 118. The PS112 may perform post-deployment calibration to compensate formisconfigured wireless access points. Additionally, the PS 112 mayassist the mobile stations 108 in determining their positions byproviding information regarding individual wireless access points and/orinformation regarding other network elements. The back end network mayalso include an interconnecting network 116 for interconnecting thelocal area network to the wide area network 118. Network 116 may be awired network as shown in FIG. 1, however in other embodiments, it maybe, either in whole or in part, a wireless network. Moreover, variousembodiments may have the PS functionality placed in another portion ofthe back end network.

The operating environment 100 may further include a wireless local areanetwork (WLAN). The WLAN may include one or more Local Area NetworkWireless Access Points (LAN-WAPs) 106. The WLAN may be used for wirelessvoice and/or data communication, as well as another independent sourceof position data. Each LAN-WAPs 106 a-106 e may connect to the back endnetwork using a wireless and/or wired manner. For example, as shown inFIG. 1, LAN-WAPs 106 a-106 c may interface to the wide area network 118over the interconnecting network 116, while the LAN-WAPs 106 d and 106 emay communicate to the back-end network using a wireless connection.When in range, each mobile station 108 a-108 c may wirelessly exchangepackets with one or more LAN-WAPs 106. The WLAN may typically operate inbuildings and perform communications over smaller geographic regionsthan a WWAN, and it may operate under the protocols of a Wi-Fi network(IEEE 802.11x), Bluetooth Network, a femtocell, etc.

The mobile stations 108 may derive other independent positioninformation from any one or a combination of the SPS transmitters 102,the WAN-WAPs 104, and/or the LAN-WAPs 106. Each of the aforementionedsystems can provide an independent estimate of the position for mobilestations 108 using different techniques. In some embodiments, the mobilestations 108 may combine the solutions derived from each of thedifferent types of transmitters/access points to improve the accuracy ofthe position data. In the section below, details for conventionallydetermining the position of the mobile stations 108 are brieflypresented.

Further referring to FIG. 1, the mobile stations 108 may berepresentative of any type of portable wireless device. Thus, by way ofexample but not limitation, mobile stations 108 may include a radiodevice, a cellular telephone device, a computing device, a personalcommunication system (PCS) device, or other like movable wirelesscommunication equipped device, appliance, or machine.

As used herein, the term “wireless device” may refer to any type ofwireless communication device which may transfer information over anetwork and also have position determination and/or navigationfunctionality. The wireless device may be any mobile station, cellularmobile terminal, personal communication system (PCS) device, personalnavigation device, laptop, personal digital assistant, or any othersuitable mobile device capable of receiving and processing networkand/or SPS signals.

When deriving position data using the SPS, the mobile stations 108 mayutilize a receiver specifically designed for use with the SPS thatextracts position, using conventional techniques, from a plurality ofsignals transmitted by available SPS transmitters 102. The transmittersmay be positioned to enable entities to determine their location on orabove the Earth based, at least in part, on signals received from thetransmitters. Such a transmitter typically transmits a signal markedwith a repeating pseudo-random noise (PN) code of a set number of chipsand may be located on ground based control stations, user equipmentand/or space vehicles. In a particular example, such transmitters may belocated on Earth orbiting satellite vehicles (SVs). For example, a SV ina constellation of Global Navigation Satellite System (GNSS) such asGlobal Positioning System (GPS), Galileo, Glonass or Compass maytransmit a signal marked with a PN code that is distinguishable from PNcodes transmitted by other SVs in the constellation (e.g., usingdifferent PN codes for each satellite as in GPS or using the same codeon different frequencies as in Glonass). In accordance with certainaspects, the techniques presented herein are not restricted to globalsystems (e.g., GNSS) for SPS. For example, the techniques providedherein may be applied to or otherwise enabled for use in variousregional systems, such as, e.g., Quasi-Zenith Satellite System (QZSS)over Japan, Indian Regional Navigational Satellite System (IRNSS) overIndia, Beidou over China, etc., and/or various augmentation systems(e.g., an Satellite Based Augmentation System (SBAS)) that may beassociated with or otherwise enabled for use with one or more globaland/or regional navigation satellite systems. By way of example but notlimitation, an SBAS may include an augmentation system(s) that providesintegrity information, differential corrections, etc., such as, e.g.,Wide Area Augmentation System (WAAS), European Geostationary NavigationOverlay Service (EGNOS), Multi-functional Satellite Augmentation System(MSAS), GPS Aided Geo Augmented Navigation or GPS and Geo AugmentedNavigation system (GAGAN), and/or the like. Thus, as used herein an SPSmay include any combination of one or more global and/or regionalnavigation satellite systems and/or augmentation systems, and SPSsignals may include SPS, SPS-like, and/or other signals associated withsuch one or more SPS.

Furthermore, the disclosed method and apparatus may be used withpositioning determination systems that utilize pseudolites or acombination of satellites and pseudolites. Pseudolites are ground-basedtransmitters that broadcast a PN code or other ranging code (similar toa GPS or CDMA cellular signal) modulated on an L-band (or otherfrequency) carrier signal, which may be synchronized with GPS time. Eachsuch transmitter may be assigned a unique PN code so as to permitidentification by a remote receiver. Pseudolites are useful insituations where signals from an orbiting satellite might beunavailable, such as in tunnels, mines, buildings, urban canyons orother enclosed areas. Another implementation of pseudolites is known asradio-beacons. The term “satellite”, as used herein, is intended toinclude pseudolites, equivalents of pseudolites, and possibly others.The term “SPS signals,” as used herein, is intended to include SPS-likesignals from pseudolites or equivalents of pseudolites.

When deriving position from the WWAN, each WAN-WAPs 104 a-104 c may takethe form of base stations within a digital cellular network, and themobile station 108 may include a cellular transceiver and processingunit that can exploit the base station signals to derive position. Itshould be understood that a digital cellular network may includeadditional base stations or other resources not shown in FIG. 1. WhileWAN-WAPs 104 may actually be moveable or otherwise capable of beingrelocated, for illustration purposes it will be assumed that they areessentially arranged in a fixed position. The mobile stations 108 mayalso perform position determination using conventional time-of-arrivaltechniques such as, for example, Advanced Forward Link Trilateration(AFLT). In other embodiments, any WAN-WAP 104 a-104 c may take the formof a WiMAX wireless networking base station. For example, the mobilestations 108 may determine its position using time-of-arrival (TOA)techniques from signals provided by the WAN-WAPs 104. The mobilestations 108 may determine positions either in a stand-alone mode, orusing the assistance of positioning server 112 and/or the wide areanetwork 118 using conventional TOA techniques. Note that embodiments ofthe disclosure may include having the mobile stations 108 determineposition information using WAN-WAPs 104 which are different types. Forexample, some WAN-WAPs 104 may be cellular base stations, and otherWAN-WAPs may be WiMAX base stations. In such an operating environment,the mobile station 108 may be able to exploit the signals from eachdifferent type of WAN-WAP, and further combine the derived positionsolutions to improve accuracy.

When deriving independent position information of any mobile stationbased upon conventional techniques using the WLAN, such mobile stations108 may utilize time of arrival and/or signal strength techniques withthe assistance of the positioning server 112 and the wide area network118. The conventional position determination techniques may also be usedin conjunction with other various wireless communication networks suchas a wireless wide area network (WWAN), a wireless local area network(WLAN), a wireless personal area network (WPAN), and so on.

The term “network” and “system” are often used interchangeably. A WWANmay be a Code Division Multiple Access (CDMA) network, a Time DivisionMultiple Access (TDMA) network, a Frequency Division Multiple Access(FDMA) network, an Orthogonal Frequency Division Multiple Access (OFDMA)network, a Single-Carrier Frequency Division Multiple Access (SC-FDMA)network, a Long Term Evolution (LTE) network, a WiMAX (IEEE 802.16)network, and so on. A CDMA network may implement one or more radioaccess technologies (RATs) such as cdma2000, Wideband-CDMA (W-CDMA), andso on. Cdma2000 includes IS-95, IS-2000, and IS-856 standards. A TDMAnetwork may implement Global System for Mobile Communications (GSM),Digital Advanced Mobile Phone System (D-AMPS), or some other RAT. GSMand W-CDMA are described in documents from a consortium named “3rdGeneration Partnership Project” (3GPP). Cdma2000 is described indocuments from a consortium named “3rd Generation Partnership Project 2”(3GPP2). 3GPP and 3GPP2 documents are publicly available. A WLAN may bean IEEE 802.11x network, and a WPAN may be a Bluetooth network, an IEEE802.15x, or some other type of network. The techniques may also be usedfor any combination of WWAN, WLAN and/or WPAN.

The above described localization techniques, as well as any other knownconventional position determination approaches, may be used inconjunction with various network centric position determinationembodiments to improve accuracy and/or performance. Network centricembodiments which may utilize conventionally determined localizationinformation will be described in more detail in subsequent sections ofthe description.

FIG. 2 is a block diagram illustrating various components of anexemplary mobile station 200. For the sake of simplicity, the variousfeatures and functions illustrated in the diagram of FIG. 2 areconnected together using a common bus which is meant to represent thatthese various features and functions are operatively coupled together.Those skilled in the art will recognize that other connections,mechanisms, features, functions, or the like, may be provided andadapted as necessary to operatively couple and configure an actualportable wireless device. Further, it is also recognized that one ormore of the features or functions illustrated in the example of FIG. 2may be further subdivided or two or more of the features or functionsillustrated in FIG. 2 may be combined.

The mobile station may include one or more wide area networktransceiver(s) 204 that may be connected to one or more antennas 202.The wide area network transceiver 204 comprises suitable devices,hardware, and/or software for communicating with and/or detectingsignals to/from WAN-WAPs 104, and/or directly with other wirelessdevices within a network. In one aspect, the wide area networktransceiver 204 may comprise a CDMA communication system suitable forcommunicating with a CDMA network of wireless base stations; however inother aspects, the wireless communication system may comprise anothertype of cellular telephony network, such as, for example, TDMA or GSM.Additionally, any other type of wireless networking technologies may beused, for example, WiMAX (802.16), etc. The mobile station may alsoinclude one or more local area network transceivers 206 that may beconnected to one or more antennas 202. The local area networktransceiver 206 comprises suitable devices, hardware, and/or softwarefor communicating with and/or detecting signals to/from LAN-WAPs 106,and/or directly with other wireless devices within a network. In oneaspect, the local area network transceiver 206 may comprise a Wi-Fi(802.11x) communication system suitable for communicating with one ormore wireless access points; however in other aspects, the local areanetwork transceiver 206 comprise another type of local area networktechnology, personal area network technology (e.g., Bluetooth), etc.Additionally, any other type of wireless networking technologies may beused, for example, Ultra Wide Band, ZigBee, wireless USB, etc.

As used herein, the term “wireless access point” (WAP) may be used torefer to LAN-WAPs 106, femtocells, and/or WAN-WAPs 104, Bluetoothtransceivers, etc. Specifically, in the description presented below,when the term “WAP” is used, it should be understood that embodimentsmay include a mobile station 200 that can exploit signals from aplurality of LAN-WAPs 106, a plurality of WAN-WAPs 104, femtocells, orany combination of technologies. The specific type of WAP being utilizedby the mobile station 200 may depend upon the environment of operation.Moreover, the mobile station 200 may dynamically select between thevarious types of WAPs in order to arrive at an accurate positionsolution.

An SPS receiver 208 may also be included in mobile station 200. The SPSreceiver 208 may be connected to the one or more antennas 202 forreceiving SPS signals. The SPS receiver 208 may comprise any suitablehardware and/or software for receiving and processing SPS signals. TheSPS receiver 208 may request information and operations as appropriatefrom the other systems, and perform the calculations necessary todetermine the mobile station 200's position using measurements obtainedby any suitable SPS algorithm.

A motion sensor 212 may be coupled to processing unit 210 to providerelative movement and/or orientation information which is independent ofmotion data derived from signals received by the wide area networktransceiver 204, the local area network transceiver 206 and the SPSreceiver 208. By way of example but not limitation, motion sensor 212may utilize an accelerometer (e.g., a MEMS device), a gyroscope, ageomagnetic sensor (e.g., a compass), an altimeter (e.g., a barometricpressure altimeter), and/or any other type of movement detection sensor.Moreover, motion sensor 212 may include a plurality of different typesof devices and combine their outputs in order to provide motioninformation.

A processing unit 210 may be connected to the wide area networktransceiver 204, local area network transceiver 206, the SPS receiver208 and the motion sensor 212. The processing unit may include one ormore microprocessors, microcontrollers, and/or digital signal processorsthat provide processing functions, as well as other calculation andcontrol functionality. The processor 210 may also include memory 214 forstoring data and software instructions for executing programmedfunctionality within the mobile station. The memory 214 may be on-boardthe processing unit 210 (e.g., within the same IC package), and/or thememory 214 may be external to the processing unit and functionallycoupled over a data bus. The details of software functionalityassociated with aspects of the disclosure will be discussed in moredetail below.

A number of software modules and/or data tables may reside in memory 214and be utilized by the processing unit 210 in order to managecommunications and positioning determination functionality.Additionally, in one embodiment, the mobile station 200 may performpost-deployment calibration, as will be described in more detail below.Further referring to FIG. 2, memory 214 may include and/or otherwisereceive a positioning module 216, an application module 218, a receivedsignal strength indicator (RSSI) module 220, a round trip time (RTT)module 222, and an optional calibration module 228 (illustrated indashed lines). One should appreciate that the organization of the memorycontents as shown in FIG. 2 is merely exemplary, and as such thefunctionality of the modules and/or data structures may be combined,separated, and/or be structured in different ways depending upon theimplementation of the mobile station 200.

The application module 218 may be a process running on the processingunit 210 of the mobile device 200, which requests position informationfrom the positioning module 216. Applications typically run within anupper layer of the software architectures, and may include IndoorNavigation, Buddy Locator, Shopping and Coupons, Asset Tracking, andlocation Aware Service Discovery. The positioning module 216 may derivethe position of the mobile device 200 using information derived fromvarious wireless signal models, and optionally from the calibrationmodule 228. The wireless signal models may include, for example, an RTTmodel which may use the round trip times measured from signals exchangedwith a plurality of WAPs. In order to accurately determine positionusing RTT techniques, reasonable estimates of a variety of parametersassociated with each WAP should be known, and may determined using thecalibration techniques described herein. The measured RTTs may bedetermined by the RTT module 222, which can measure the timings ofsignals exchanged between the mobile station 200 and the WAPs to deriveRTT information. Once measured, the RTT values may be passed to thepositioning module 216 to assist in determining the position of themobile device 200.

The positioning module 216 may utilize other wireless signal models andcorresponding measurements for position determination. In oneembodiment, the amplitude values of the signals transmitted by the WAPsmay be used to provide signal strength information. These amplitudevalues may be determined in the form of RSSI measurements determined byRSSI module 220. The RSSI module 220 may provide amplitude andstatistical information regarding the signals to the position module216. Other signal models may use angle of arrival (AoA) to provide angleinformation which may also be utilized. The positioning module 216 mayuse such information to accurately determine position. The position maythen be output to the application module 218 in response to itsaforementioned application program request. In addition, the positioningmodule 216 may utilize a parameter database 224 for exchangingoperational parameters. Such parameters may include the determinedprocessing times for each WAP, the WAPs' positions in a commoncoordinate frame, various parameters associated with the network,initial processing time estimates, processing time estimates determinedpreviously, etc.

In some embodiments, the mobile station may perform post-deploymentcalibration using the optional calibration module 228. The calibrationmodule may refine various parameters which are used in one or morewireless signal models in order to compensate for misconfigured wirelessaccess points. The calibration module may directly utilize RTTinformation from RTT module 222, position information of the mobilestation 200 from positioning module 216, and/or RSSI information fromRSSI module 220. The calibration module may also use AoA information,which may be determined using signal phase information and/or multipleantenna techniques. For example, determining the wireless signal modelparameter may comprise determining AoA measurements based upon signalsfrom the misconfigured wireless access point. Additional information,such as, for example, known locations of one or more wireless accesspoints, may be obtained from parameter database 224. The calibrationmodule 228 may refine and/or correct information associated with one ormore wireless access points, and then provide this information back tothe positioning module 216 for more accurate position determination ofthe mobile station. This calibration solution(s) may also be stored inparameter database 224 to update/improve the accuracy of informationstored therein.

In other embodiments, other information can also aid positiondetermination, and may optionally include auxiliary position and/ormotion data which may be determined from other sources. The auxiliaryposition data may be incomplete or noisy, but may be useful as anothersource of independent information for estimating the processing times ofthe WAPs. As illustrated in FIG. 2 using dashed lines, mobile device 200may optionally store auxiliary position/motion data 226 in memory whichmay be derived from information received from other sources as describedbelow. Moreover, in other embodiments, other information may include,but not be limited to, information that can be derived or based uponBluetooth signals, beacons, RFID tags, and/or information derived frommap (e.g., receiving coordinates from a digital representation of ageographical map by, for example, a user interacting with a digitalmap).

In one embodiment, all or part of auxiliary position/motion data 226 maybe derived from information supplied by motion sensor 212 and/or SPSreceiver 208. In other embodiments, auxiliary position/motion data 226may be determined through additional networks using non-RTT techniques(e.g., AFLT within a CDMA network). In certain implementations, all orpart of auxiliary position/motion data 226 may also be provided by wayof motion sensor 212 and/or SPS receiver 208 without further processingby processing unit 210. In some embodiments, the auxiliaryposition/motion data 226 may be directly provided by the motion sensor212 and/or SPS receiver 208 to the processing unit 210. Position/motiondata 226 may also include acceleration data and/or velocity data whichmay provide direction and speed. In other embodiments, position/motiondata 226 may further include directionality data which may only providedirection of movement.

While the modules shown in FIG. 2 are illustrated in the example asbeing contained in memory 214, it is recognized that in certainimplementations such procedures may be provided for or otherwiseoperatively arranged using other or additional mechanisms. For example,all or part of calibration module 228, positioning module 216 and/orapplication module 218 may be provided in firmware. Additionally, whilein this example positioning module 216 and calibration module 228 areillustrated as being separate features, it is recognized, for example,that such procedures may be combined together as one procedure orperhaps with other procedures, or otherwise further divided into aplurality of sub-procedures.

Processing unit 210 may include any form of logic suitable forperforming at least the techniques provided herein. For example,processing unit 210 may be operatively configurable based oninstructions in memory 214 to selectively initiate one or more routinesthat exploit motion data for use in other portions of the mobile device.

The mobile station 200 may include a user interface 250 which providesany suitable interface systems, such as a microphone/speaker 252, keypad254, and display 256 that allows user interaction with the mobilestation 200. The microphone/speaker 252 provides for voice communicationservices using the wide area network transceiver 204 and/or the localarea network transceiver 206. The keypad 254 comprises any suitablebuttons for user input. The display 256 comprises any suitable display,such as, for example, a backlit LCD display, and may further include atouch screen for additional user input modes.

As used herein, mobile station 108 may be any portable or movable deviceor machine that is configurable to acquire wireless signals transmittedfrom, and transmit wireless signals to, one or more wirelesscommunication devices or networks. As shown in FIGS. 1 and 2, the mobiledevice is representative of such a portable wireless device. Thus, byway of example but not limitation, mobile station 108 may include aradio device, a cellular or other wireless communication device,personal communication system (PCS) device, personal navigation device(PND), Personal Information Manager (PIM), Personal Digital Assistant(PDA), laptop, a computing device, or other like movable wirelesscommunication equipped device, appliance, or machine. The term “mobilestation” is also intended to include devices which communicate with apersonal navigation device (PND), such as by short-range wireless,infrared, wire line connection, or other connection—regardless ofwhether satellite signal reception, assistance data reception, and/orposition-related processing occurs at the device or at the PND. Also,“mobile station” is intended to include all devices, including wirelesscommunication devices, computers, laptops, etc. which are capable ofcommunication with a server, such as via the Internet, Wi-Fi, or othernetwork, and regardless of whether satellite signal reception,assistance data reception, and/or position-related processing occurs atthe device, at a server, or at another device associated with thenetwork. Any operable combination of the above are also considered a“mobile station.”

As discussed above, the term “wireless device” may refer to any type ofwireless communication device which may transfer information over anetwork and also have position determination and/or navigationfunctionality. The wireless device may be any mobile station, cellularmobile terminal, personal communication system (PCS) device, personalnavigation device, laptop, personal digital assistant, or any othersuitable mobile device capable of receiving and processing networkand/or SPS signals.

Accordingly, in one embodiment, a mobile station 200 may calibrate amisconfigured wireless access point. The mobile station 200 may includea means for receiving positions associated with a plurality of wirelessaccess points (e.g., 206), a means for determining a position of themobile station 200 based upon a wireless signal model (e.g., 216), ameans for comparing the position of the mobile station 200 and thewireless signal model with the positions associated with the pluralityof wireless access points (e.g., 228); and a means for determiningwhether at least one wireless access point is misconfigured (e.g., 228).

FIG. 3 is a block diagram illustrating one exemplary embodiment of apositioning server (PS) 112. The positioning server may be a separatedevice which resides within the back end network. The PS 112 maycoordinate the reception of information provided by mobile station(s)108 to perform post-deployment calibration of one or more misconfiguredWAPs. Additionally, the PS 112 may provide information regarding networkelements to assist the mobile station 108 in determining its position.In other embodiments, the PS 112 may determine the position of one ormore mobile stations 108 using network centric methods. Once the PS 112calibrates at least one WAP, the corrected parameter(s) may be providedback to the mobile device, and/or stored in a local parameter databasefor future use. When the PS 112 may typically reside on the back endnetwork, in some embodiments, such calibration capability may beoptionally incorporated into one or more WAPs having been modified toperform the calibration functionality.

For the sake of simplicity, the various features and functionsillustrated in the block diagram of FIG. 3 are connected together usinga common bus which is meant to represent that these various features andfunctions are operatively coupled together. Those skilled in the artwill recognize that other connections, mechanisms, features, functions,or the like, may be provided and adapted as necessary to operativelycouple and configure an actual PS. Further, it is also recognized thatone or more of the features or functions illustrated in the example ofFIG. 3 may be further subdivided or two or more of the features orfunctions illustrated in FIG. 3 may be combined.

The PS 112 may include a network interface 305 that may be wired and/orwireless for communicating over a WAN and/or LAN. In one embodiment, thePS 112 may communicate over with other network elements in the back endnetwork via WAN 118, which may include communications with WWAN via thegateway 120. The PS may also communicate using network interface 305over the WAN 118 and/or interconnecting network 116 to exchangeinformation with one or more WAPs. The network interface 305 may utilizeany known wired networking technology (e.g., Ethernet) and/or wirelesstechnology (e.g., Wi-Fi (IEEE 802.11x)).

A processing unit 310 may be connected to the network interface 305, auser interface 315 and memory 320. The processing unit 310 may includeone or more microprocessors, microcontrollers, and/or digital signalprocessors that provide processing functions, as well as othercalculation and control functionality. The processing unit 310 mayaccess memory 320 for reading/writing data and/or software instructionsfor executing programmed functionality. The memory 320 may be on-boardthe processing unit 310 (e.g., within the same IC package), and/or thememory may be external to the processing unit and functionally coupledover a data bus.

A number of software modules and/or data tables may reside in memory 320and be utilized by the processing unit 310 for managing both WAPcoordination and/or positioning determination functionality. Asillustrated here, within memory 320, the PS 112 may further include orotherwise provide a coordination module 325, a calibration module 330, apositioning module 335 and/or a parameter database 340. The coordinationmodule 325 may interrogate and/or receive information from one or moremobile stations 108. Such information may include the mobile station'sself-derived position, and information it used to derive its position.This information may be requested by the PS 112, or it may be pusheddown at the initiative of the mobile station 108. When requested by thePS 112, a mobile station may provide, for example, packet derived RTTand/or RSSI measurements, identification of the WAPs used to deriveposition, positions of each WAP used by the mobile station 108 todetermine position, etc. Once this information is received by the PS112, the coordination module 325 may perform further processing and thenpass the information on to the calibration module 330. The calibrationmodule may analyze the received information to identify a misconfiguredWAP. If the received information contains sufficient information from aplurality of mobile stations, the calibration module 330 may combinetheir measurements and correct parameters in one or more misconfiguredWAPs. For example, if a WAP was misconfigured with the wrong position,the calibration module 330, in conjunction with positioning module 335,may use the position of a plurality of mobile stations to determine thecorrect position of the misconfigured WAP. Once the parameter(s) arecalibrated for one or more misconfigured WAPs, these parameter(s) may besent back to the mobile station(s) 108, and/or the correctedparameter(s) may be stored in parameter database 340 for future use.

While the software modules shown in FIG. 3 are illustrated in theexample as being contained in memory 320, it should be recognized thatin certain implementations such procedures may be provided for orotherwise operatively arranged using other or additional mechanisms. Forexample, all or part of coordination module 325, calibration module 330,parameter database 340 and/or positioning module 335 may be provided infirmware. Additionally, while in FIG. 3 the modules are shown asdistinct entities, it should be understood that, for example, theillustrated modules may be combined together as one procedure, orperhaps with other modules not illustrated, or otherwise be furtherpartitioned into differing groups of procedures.

Accordingly, an embodiment may include an apparatus (e.g., 112) forcalibrating a misconfigured wireless access point used for determining aposition of a mobile station 108. The apparatus 112 may include a meansfor receiving a position of a mobile station(s) 108 (e.g., 305), andwireless signal model measurements derived from packets exchangedbetween the mobile station(s) and a plurality of wireless access points(e.g., 305), a means for receiving positions and/or identities of theplurality of wireless access points used in determining the position ofthe at least one mobile station 108 (e.g., 305), a means for comparing aposition of the at least one mobile station with wireless signal modelmeasurements (e.g., 330), and means for identifying a misconfiguredwireless access point based upon the comparing (e.g., 330).

FIG. 4 illustrates an exemplary embodiment showing a number of LocalArea Network-Wireless Access Points (LAN-WAPs) communicating with amobile station, wherein one LAN-WAP may be misconfigured. In FIG. 4, themobile station 108 may communicate with a plurality of LAN-WAPs 311 byexchanging packets over wireless signals. In this example, mobilestation 108 may be positioned at location (X, Y) and may communicatewith LAN-WAP1 311 a, LAN-WAP2 311 b, LAN-WAP3 311 c via wireless links.In this example, LAN-WAP1 311 a and LAN-WAP2 311 b are properlyconfigured with respect to their position. However, LAN-WAP3 311 c ismisconfigured with respect to its position. While this exemplaryembodiment illustrates three LAN-WAPs, it is understood that this ismerely exemplary and any number of LAN-WAPs and/or wireless links may beutilized.

Further referring to FIG. 4 in more detail, LAN-WAP1 311 a may bepositioned at location (X₁, Y₁) and LAN-WAP2 311 b may be positioned atlocation (X₂, Y₂), where each of these positions reflects their truelocation. The mobile station 108 “believes” LAN-WAP3 311 c is aterroneous position (X_(3err), Y_(3err)); however, its actual position isat (X_(3act), Y_(3act). The positions of each LAN-WAP that are used bythe mobile station may be reported by the respective LAN-WAP in a beaconsignal. Additionally, the LAN-WAP positions may be read from datastructures stored in the parameter database 224 within the mobilestation 108 and/or the parameter database 340 within the PS 112. In someembodiments, database may store the positions in the form of annotatedmaps.

The positions of the LAN-WAPs, along with their respective signalmeasurements, may be used along with one or more wireless models toderive the position of the mobile station 108. The signal measurementsmade using packets exchanged between mobile station 108 and LAN-WAP1 311a, LAN-WAP2 311 b, and LAN-WAP3 311 c can provide the respectivedistances d₀₁, d₀₂, and d₀₃. Mobile station 108 may measure thesedistances utilizing ranging techniques based upon one or more wirelesssignal models (e.g., RTT and/or RSSI ranging models) and/or furtherrefine their location (e.g., using AoA models). For example, mobilestation 108 may send packets of data to a plurality of local LAN-WAPs311. The local LAN-WAPs 311 can process the packets of data and sendresponses back to the mobile station 108. Mobile station 108 may thenestimate the RTT associated with the exchanged packets. The RTT can bethe time elapsed between the transmission of a packet of data sent fromthe mobile station 108 to any of the LAN-WAPs 311 and the correspondingacknowledgement (ACK) received from the corresponding LAN-WAPs 311.Exemplary RTT/RSSI models are described in co-pending patent application“WIRELESS POSITION DETERMINATION USING ADJUSTED ROUND TRIP TIMEMEASUREMENTS” by Aggarwal et al. (Ser. No. 12/622,289), which has beenincorporated herein by reference.

Angle of Arrival information may be determined using conventionaltechniques, which may include, for example, exploiting signal phaseinformation, multiple channels and/or signals received and combined frommultiple wireless access points to estimate the angle of arrivalinformation associated with the received signal. The angel of arrivalinformation may be utilized to initially isolate the position of amisconfigured wireless access point. For example, angle of arrivalinformation may be used as a “trigger” to indicate whether a LAN-WAP hasmoved from its previous position.

When determining the position of the mobile station 108, each of thedetermined distances d₀₁, d₀₂, and d₀₃ may define the radius of acircle. The center of each circle may be defined by the position of eachLAN-WAP. The intersection of the circles may provide the location (x, y)of the mobile station 108. As can be seen in FIG. 4, the circle definedby radius d₀₃ and center (X_(3err), Y_(3err)) is improperly shiftedbecause of the location error of LAN-WAP3 311 c. This shift can reducethe accuracy of the position solution. The calibration techniquesdescribed herein can ascertain that LAN-WAP3 is misconfigured, and aswill be described below in FIG. 5, may be able to estimate the actualposition (X_(3act), Y_(3act)) of LAN-WAP3 311 c to improve the accuracyof the position determination process used to locate the mobile station108.

FIG. 5 is a diagram showing an embodiment where the positioning server112 may estimate the actual position of the misconfigured LAN-WAP3 311 cusing information derived from a plurality of mobile stations 108. Eachmobile station 108 a, 108 b, and 108 c may provide its position, (x_(a),y_(a)), (x_(b), y_(b)), and (x_(c), y_(c)), respectively, to positioningserver 112. In addition, each mobile station 108 a-108 c may providemeasurements (e.g., RTT and/or RSSI) so that the distances (d3_(a),d3_(b), d3_(c), respectively) between each mobile station and themisconfigured LAN-WAP3 311 c may be determined. By knowing each distanceand the locations of each mobile station 108 a-108 c, the actualposition (X_(3act), Y_(3act)) of the misconfigured LAN-WAP3 311 c may bedetermined using known techniques, such as, for example, trilateration.

Because the positions of each mobile station 108 a-108 c initiallyprovided to the PS 112 may be inaccurate due to using (X_(3err),Y_(3err)) in their determination, the PS 112 may iterate upon the actualposition (X_(3act), Y_(3act)) of LAN-WAP3 311 c, where each successiveestimate of the LAN-WAP3 311 c position may be refined by using updatedpositions of each mobile station 108 a-108 c, which are computed using aprior estimate of the actual position (X_(3act), Y_(3act)) of LAN-WAP3311 c.

In order to estimate the position of the misconfigured LAN-WAP 311 c inthree-dimensions, the positioning server 112 should have informationfrom at least three mobile stations.

FIG. 6 is a flow chart 600 illustrating an embodiment of a calibrationprocess which may be performed by the positioning server (PS) 112.Initially, the PS 112 may receive from at least one mobile station 108 aposition estimate thereof, where this position may be determined by themobile station itself (605). Additionally, the PS 112 may receivewireless signal model measurements from mobile station 108, which areassociated with packet exchanges with the WAPs used in the determinationof the mobile station's position (605). These measurements may includeRTT and/or RSSI measurements and wireless signal model measurementsderived from packets exchanged between the at least one mobile stationand a plurality of WAPs. In other embodiments, the wireless signal modelmeasurements may include angle of arrival measurements to one or moreWAPs.

The PS 112 may further receive, from the mobile station, positionsand/or identities of the WAPs which may have been used for determiningthe position of the mobile station(s) (610). The positions of each WAPmay have been reported to the mobile station 108 via a beacon signal.Alternatively, the positions of the WAPs may be determined via adatabase (e.g., parameter database 224) and/or an annotated map (whichmay also be stored in a database). The positions associated with theWAPs may be provided by the back end network. Exemplary techniques forproviding the mobile station 108 with the positions of the WAPs aredescribed in co-pending patent application “A METHOD AND APPARATUS FORPROVIDING AND UTILIZING LOCAL MAPS AND ANNOTATIONS IN LOCATIONDETERMINATION” by Das et al. (Ser. No. 12/641,225), which has beenincorporated herein by reference.

In other embodiments, the identities of each WAP used in the positiondetermination of the mobile station 108 may be used by the mobilestation so that their positions may be retrieved from a residentdatabase (e.g., parameter database 340) (610). In further embodiments,this information may also be received, either in whole or in part, fromother database(s) functionally coupled to the network. The WAPidentities may be standard networking parameters, such as, for example,MAC addresses.

Based upon the received information, the PS 112 may compare the receivedposition of the mobile station(s) 108 with wireless signal modelmeasurements. In one embodiment, this may be accomplished by having thePS 112 determine the distances to each WAP using the wireless signalmodel measurements and the appropriate wireless signal model(hereinafter referred to as “measured distances”). A correspondinggeometric distance between each WAP and mobile station(s) 108 may becomputed by the PS 112 using the received positions of the mobilestation(s) and each WAP. The PS 112 may compare the computed geometricdistance with its corresponding measured distance to detect significantdeviations (615). The comparisons may be combined to determine at leastone misconfigured wireless access point from the plurality of wirelessaccess points. If the PS 112 finds significant deviations (which may bedetermined, for example, using thresholding and/or other statisticaltechniques), the WAP associated with the geometric distances can beidentified as a misconfigured wireless access point (620). Ifinformation is received from a plurality of mobile stations 108, awireless signal model parameter and/or a new position of themisconfigured wireless access point based upon the wireless signal modelmeasurements and positions of the plurality of mobile stations may bedetermined, and misconfigured WAP parameters (such as wireless signalmodel parameters and/or location) may be corrected (625). Thesecorrections may be performed by combining the information from theplurality of mobile stations 108. For example, as described above inFIG. 5, the position of a LAN-WAP may be calibrated by having the PS 112perform trilateration using each mobile station position and measureddistance to the misconfigured LAN-WAP. In other embodiments, statisticaltechniques may be used to calibrate timing delays and/or signal strengthparameters associated with a misconfigured WAP. The wireless signalmodel parameter may include time delays and/or signal strengthadjustments associated with the misconfigured wireless access point. Inother embodiments, the PS 112 may use the information supplied by themobile stations to detect whether the LAN-WAP was removed from thenetwork. For example, if a number of mobile stations take measurementsnear a previously determined location for WAP_(k), and none of thesemeasurements include RSSI/RTT ranging information for WAP_(k) then itmay be likely that WAP_(k) has moved, or has been disabled.

FIG. 7 is a flow chart 700 illustrating an embodiment of a calibrationprocess which may be performed by the mobile station 108. This methodmay be performed in addition to the method described above in FIG. 6.Initially, the method may start by having the mobile station receivepositions associated with a plurality of wireless access points (705).This information may be provided as described above in FIG. 6 (e.g.received in beacon signals and/or annotated maps). The mobile station108 may then determine its own position based upon at least one wirelesssignal model and associated measurements (710). The mobile station 108may then compare its position with the wireless signal model(s) todetermine if at least one misconfigured WAP is present (715). Thecomparisons may be combined to determine at least one misconfiguredwireless access point from the plurality of wireless access points. Thecomparison(s) may involve analyzing geometrically derived distances withthe distances based upon wireless measurements. The mobile station maythen determine whether the number of WAPs involved in ranging is greaterthan three (720). If so, the mobile station 108 may identify themisconfigured WAP using a process of elimination wherein the mobilestation 108 determines its position (e.g., calculate a test position)multiple times, each time removing a different WAP and using theremaining WAPs for position determination. These positions may becompared, and any outlier position of the mobile station 108 may be usedto identify the misconfigured WAP (730). If removing a WAP causes thepre-trilateration distance measurements to coincide more closely withthe post-trilateration distances, then the WAP is considered a possiblecandidate for being misconfigured. If this behavior is seen many times,and by many stations, then the likelihood of the AP being misconfiguredcontinues to increase (735).

If number of ranging WAPs is determined to be less than or equal tothree in Block 720, then the mobile station 725 may provide appropriateinformation to the back end network, where the PS 112 may be used toidentify the misconfigured WAP (725).

Those of skill in the art will appreciate that information and signalsmay be represented using any of a variety of different technologies andtechniques. For example, data, instructions, commands, information,signals, bits, symbols, and chips that may be referenced throughout theabove description may be represented by voltages, currents,electromagnetic waves, magnetic fields or particles, optical fields orparticles, or any combination thereof. It will be appreciated thatembodiments include various methods for performing the processes,functions and/or algorithms disclosed herein. For example, asillustrated in FIG. 6, an embodiment can include a method forcalibrating a misconfigured wireless access point used for determining aposition of a mobile station. The method may include receiving aposition of at least one mobile station and wireless signal modelmeasurements derived from packets exchanged between the at least onemobile station and a plurality of wireless access points. The method mayfurther include receiving positions and/or identities of the pluralityof wireless access points used in determining the position of the atleast one mobile station, comparing a position of the at least onemobile station with wireless signal model measurements, and identifyinga misconfigured wireless access point based upon the comparing. Anotherexemplary method is shown in FIG. 7, where a flow chart describing thecalibration of a misconfigured wireless access point at a mobile stationis illustrated. The method may include receiving positions associatedwith a plurality of wireless access points, and determining a positionof the mobile station based upon a wireless signal model. The method mayfurther include comparing the position of the mobile station and thewireless signal model with the positions associated with the pluralityof wireless access points, and determining whether at least one wirelessaccess point is misconfigured.

Further, those of skill in the art will appreciate that the variousillustrative logical blocks, modules, circuits, and algorithm stepsdescribed in connection with the embodiments disclosed herein may beimplemented as electronic hardware, computer software, or combinationsof both. To clearly illustrate this interchangeability of hardware andsoftware, various illustrative components, blocks, modules, circuits,and steps have been described above generally in terms of theirfunctionality. Whether such functionality is implemented as hardware orsoftware depends upon the particular application and design constraintsimposed on the overall system. Skilled artisans may implement thedescribed functionality in varying ways for each particular application,but such implementation decisions should not be interpreted as causing adeparture from the scope of the present invention.

The methodologies described herein may be implemented by various meansdepending upon the application. For example, these methodologies may beimplemented in hardware, firmware, software, or any combination thereof.For a hardware implementation, the processing units may be implementedwithin one or more application specific integrated circuits (ASICs),digital signal processors (DSPs), digital signal processing devices(DSPDs), programmable logic devices (PLDs), field programmable gatearrays (FPGAs), processors, controllers, micro-controllers,microprocessors, electronic devices, other electronic units designed toperform the functions described herein, or a combination thereof.

For a firmware and/or software implementation, the methodologies may beimplemented with modules (e.g., procedures, functions, and so on) thatperform the functions described herein. Any machine-readable mediumtangibly embodying instructions may be used in implementing themethodologies described herein. A machine may take the form of acomputer/processing unit. For example, software codes may be stored in amemory and executed by a processing unit. Memory may be implementedwithin the processor unit or external to the processor unit. As usedherein the term “memory” refers to any type of long term, short term,volatile, nonvolatile, or other memory and is not to be limited to anyparticular type of memory or number of memories, or type of media uponwhich memory is stored.

If implemented in firmware and/or software, the functions may be storedas one or more instructions or code on a computer-readable medium.Examples include computer-readable media encoded with a data structureand computer-readable media encoded with a computer program. Acomputer-readable medium may take the form of an article of manufacture.Computer-readable media includes physical computer storage media. Astorage medium may be any available medium that can be accessed by acomputer. By way of example, and not limitation, such computer-readablemedia can comprise RAM, ROM, EEPROM, CD-ROM or other optical diskstorage, magnetic disk storage or other magnetic storage devices, or anyother medium that can be used to store desired program code in the formof instructions or data structures and that can be accessed by acomputer; disk and disc, as used herein, includes compact disc (CD),laser disc, optical disc, digital versatile disc (DVD), floppy disk andBlu-ray disc where disks usually reproduce data magnetically, whilediscs reproduce data optically with lasers. Combinations of the aboveshould also be included within the scope of computer-readable media.

In addition to storage on computer readable medium, instructions and/ordata may be provided as signals on transmission media included in acommunication apparatus. For example, a communication apparatus mayinclude a transceiver having signals indicative of instructions anddata. The instructions and data are configured to cause one or moreprocessing units to implement the functions outlined in the claims. Thatis, the communication apparatus includes transmission media with signalsindicative of information to perform disclosed functions. At a firsttime, the transmission media included in the communication apparatus mayinclude a first portion of the information to perform the disclosedfunctions, while at a second time the transmission media included in thecommunication apparatus may include a second portion of the informationto perform the disclosed functions.

While the foregoing disclosure shows illustrative embodiments of theinvention, it should be noted that various changes and modificationscould be made herein without departing from the scope of the inventionas defined by the appended claims. The functions, steps and/or actionsof the method claims in accordance with the embodiments of the inventiondescribed herein need not be performed in any particular order.Furthermore, although elements of the invention may be described orclaimed in the singular, the plural is contemplated unless limitation tothe singular is explicitly stated.

What is claimed is:
 1. A method for identifying a misconfigured wirelessaccess point, comprising: determining, based on signals received from aplurality of wireless access points, a plurality of test positions of amobile station by determining a position of the mobile station for eachof a plurality of subsets of the signals received from the plurality ofwireless access points, each of the plurality of subsets of the signalsreceived from the plurality of wireless access points being unique andexcluding one of the signals received from the plurality of wirelessaccess points, wherein the plurality of wireless access points comprisesfour or more wireless access points, wherein the determining theposition of the mobile station is based on trilateration, round triptime (RTT), received signal strength indicator (RSSI), Time-of-arrival(TOA), Angle of Arrival (AoA) or any combination thereof; and comparingthe plurality of test positions to identify the misconfigured wirelessaccess point.
 2. The method of claim 1, further comprising: determiningthe position of the mobile station using the signals received from theplurality of wireless access points; and determining that at least oneof the plurality of wireless access points is misconfigured by comparingthe position of the mobile station with wireless signal modelinformation.
 3. The method of claim 2 wherein the wireless signal modelinformation includes position information associated with the pluralityof wireless access points.
 4. The method of claim 1, wherein comparingthe plurality of test positions to identify the misconfigured wirelessaccess point comprises: identifying a test position of the plurality oftest positions that is inconsistent with other test positions of theplurality of test positions; and identifying a wireless access point ofthe plurality of wireless access points associated with the testposition that is inconsistent with the other test positions.
 5. Themethod of claim 1, further comprising: sending information identifyingthe misconfigured wireless access point to a location server.
 6. Anapparatus for identifying a misconfigured wireless access point,comprising: means for determining, based on signals received from aplurality of wireless access points, a plurality of test positions of amobile station by determining a position of the mobile station for eachof a plurality of subsets of the signals received from the plurality ofwireless access points, each of the plurality of subsets of the signalsreceived from the plurality of wireless access points being unique andexcluding one of the signals received from the plurality of wirelessaccess points, wherein the plurality of wireless access points comprisesfour or more wireless access points, wherein the determining theposition of the mobile station is based on trilateration, round triptime (RTT), received signal strength indicator (RSSI), Time-of-arrival(TOA), Angle of Arrival (AoA) or any combination thereof; and means forcomparing the plurality of test positions to identify the misconfiguredwireless access point.
 7. The apparatus of claim 6, further comprising:means for determining the position of the mobile station using thesignals received from the plurality of wireless access points; and meansfor determining that at least one of the plurality of wireless accesspoints is misconfigured by comparing the position of the mobile stationwith wireless signal model information.
 8. The apparatus of claim 7wherein the wireless signal model information includes positioninformation associated with the plurality of wireless access points. 9.The apparatus of claim 6, wherein the means for comparing the pluralityof test positions to identify the misconfigured wireless access pointfurther comprises: means for identifying a test position of theplurality of test positions that is inconsistent with other testpositions of the plurality of test positions; and means for identifyinga wireless access point of the plurality of wireless access pointsassociated with the test position that is inconsistent with the othertest positions.
 10. The apparatus of claim 6, further comprising: meansfor sending information identifying the misconfigured wireless accesspoint to a location server.
 11. A non-transitory computer-readablemedium having stored thereon computer-readable instructions foridentifying a misconfigured wireless access point by being configured tocause a computer to: determine, based on signals received from aplurality of wireless access points, a plurality of test positions of amobile station by determining a position of the mobile station for eachof a plurality of subsets of the signals received from the plurality ofwireless access points, each of the plurality of subsets of the signalsreceived from the plurality of wireless access points being unique andexcluding one of the signals received from the plurality of wirelessaccess points, wherein the plurality of wireless access points comprisesfour or more wireless access points, wherein the determining theposition of the mobile station is based on trilateration, round triptime (RTT), received signal strength indicator (RSSI), Time-of-arrival(TOA), Angle of Arrival (AoA) or any combination thereof; and comparethe plurality of test positions to identify the misconfigured wirelessaccess point.
 12. The non-transitory computer-readable medium of claim11, further comprising instructions configured to cause the computer to:determine the position of the mobile station using the signals receivedfrom the plurality of wireless access points; and determine that atleast one of the plurality of wireless access points is misconfigured bycomparing the position of the mobile station with wireless signal modelinformation.
 13. The non-transitory computer-readable medium of claim 12wherein the wireless signal model information includes positioninformation associated with the plurality of wireless access points. 14.The non-transitory computer-readable medium of claim 11, wherein theinstructions configured to cause the computer to compare the pluralityof test positions to identify the misconfigured wireless access pointfurther comprise instructions configured to cause the computer to:identify a test position of the plurality of test positions that isinconsistent with other test positions of the plurality of testpositions; and identify a wireless access point of the plurality ofwireless access points associated with the test position that isinconsistent with the other test positions.
 15. The non-transitorycomputer-readable medium of claim 11, further comprising instructionsconfigured to cause the computer to: send information identifying themisconfigured wireless access point to a location server.
 16. A mobilestation for identifying a misconfigured wireless access point,comprising: a receiver configured to receive signals from a plurality ofwireless access points; and a processor configured to determine, basedon signals received from a plurality of wireless access points, aplurality of test positions of the mobile station by determining aposition of the mobile station for each of a plurality of subsets of thesignals received from the plurality of wireless access points, each ofthe plurality of subsets of the signals received from the plurality ofwireless access points being unique and excluding one of the signalsreceived from the plurality of wireless access points, the processorbeing further configured to compare the plurality of test positions toidentify the misconfigured wireless access point, wherein the pluralityof wireless access points comprises four or more wireless access points,wherein the determining the position of the mobile station is based ontrilateration, round trip time (RTT), received signal strength indicator(RSSI), Time-of-arrival (TOA), Angle of Arrival (AoA) or any combinationthereof.
 17. The mobile station of claim 16 wherein the processor isfurther configured to: determine the position of the mobile stationusing the signals received from the plurality of wireless access points;and determine that at least one of the plurality of wireless accesspoints is misconfigured by comparing the position of the mobile stationwith wireless signal model information.
 18. The mobile station of claim17 wherein the wireless signal model information includes positioninformation associated with the plurality of wireless access points. 19.The mobile station of claim 16 wherein the processor being configured tocompare the plurality of test positions to identify the misconfiguredwireless access point is further configured to: identify a test positionof the plurality of test positions that is inconsistent with other testpositions of the plurality of test positions; and identify a wirelessaccess point of the plurality of wireless access points associated withthe test position that is inconsistent with the other test positions.20. The mobile station of claim 16 wherein the processor is furtherconfigured to: send information identifying the misconfigured wirelessaccess point to a location server.